Human stem-progenitor cells from neonatal cord blood have greater hematopoietic expansion capacity than those from mobilized adult blood

Objective. In this study we compared the hematopoietic capacity of CD34(+) cell preparations from neonatal cord blood (CB) vs adult mobilized peripheral blood (PBSC) before and after ex vivo culture. Methods. CD34(+) cell preparations purified from CB or PBSC were cultured in serum-free medium containing FKT: FI.T-3 ligand (FL), KIT ligand (KL), and thrombopoietin (TPO). Results. After 1-4 weeks ex vivo culture, CB CD34(+) cell preparations had greatly increased numbers of total cells, CD34(+) cells, and colony-forming cells (CFC). In contrast, ex vivo-cultured PBSC CD34(+) cell preparations generated far less in vitro assessed hematopoietic capacity. Nonobese diabetic severe combined immunodeficient mouse (NOD/SCID) engrafting potential (SEP) was maintained in ex vivo-cultured CB CD34(+) cell preparations, whereas ex vivo-cultured PBSC lost SEP. CB CD34(+) cells continued to proliferate throughout 3 weeks ex vivo, whereas after 1 week, no additional cell divisions were detected in PBSC CD34(+) cells. After 3 weeks in culture, the average CB CD34(+) cell had divided more than 5 times, as compared to only 2 times for the average PBSC CD34(+) cell. Conclusion. CB CD34(+) cell preparations generated massively increased in vitro assessed hematopoietic capacity and maintained SEP during 1- to 4-week ex vivo cultures. In contrast, ex vivo-cultured PBSC CD34(+) cell preparations generated far less in vitro assessed hematopoietic capacity and decreased SEP. The differences in the in vitro proliferative indices of membrane dye-labeled CD34(+) cells from CB vs PBSC correlated with these functional differences. (C) 2002 International Society for Experimental Hematology. Published by Elsevier Science Inc.